A new Modular Cable Modem Termination System (M-CMTS) architecture has been developed for the Data Over Cable Service Interface Specification (DOCSIS) environment that is described in co-pending application Ser. No. 11/134,818, filed May 20, 2005, entitled “TIMING SYSTEM FOR MODULAR CABLE MODEM TERMINATION SYSTEM” which is herein incorporated by reference.
One characteristic of the Modular CMTS architecture is that the DOCSIS Media Access Control (MAC) and Physical Interface (PHY) are located in different chassis and connected together through any type of packet switched network, such as a Gigabit Ethernet (GE), 10GE, or Multi-Protocol Label Switching (MPLS). In one embodiment, the DOCSIS MAC is located in the M-CMTS Core and the PHY is located in an Edge Quadrature Amplitude Modulation (EQAM) device. The interface in the downstream direction between the M-CMTS Core and the EQAM device is referred to as the Downstream External PHY Interface (DEPI), and as described above, may be established over a Gigabit Ethernet network or some other type of packet switched Internet Protocol (IP) network.
The intervening GE network between the MAC and PHY is alternatively referred to as a Converged Interconnect Network (CIN) and typically comprises one or more Layer-2 (L2) bridges and/or Layer-3 (L3) routers. In the M-CMTS architecture, multiple different Ethernet connections may be connected over the CIN between one or more M-CMTS Cores and one or more EQAM devices.
Bridging and routing protocols try and choose the best links on intermediate hops between these different layer-2 and layer-3 switching devices. This can result in the over subscription of some links and the under subscription of other links. For example, the intermediate CIN network may have a small number of source and destination MAC addresses that may not evenly distribute traffic due to hashing on the limited number of MAC addresses. Similar uneven load distribution may be created by layer-3 load balancing algorithms. In either case, bandwidth capability in the CIN can be negatively impacted by the packet switching devices between the M-CMTS Core and the EQAM device.
The present invention addresses this and other problems associated with the prior art.